RTFM.

There's many gliders out there that according to the maintenance manual
have to have certain types of sealing for (mostly) ailerons and elevator.
This is for a reason (as the guy with the DG600 pointed out, and I can also
claim a close call in an LS4 where I lost control at high speed due to a
mylar sealing peeling away partially, cost me 2000 feet to get it back,
nearly bailed out).

As an inspector I find that seals are probably the single most neglected
bit of glider maintenance. There's actually a couple of countries in EUrope
specifically warning about the possible aerodynamic consequences of
sealings missing or (worse) partially coming off. Older (wooden) gliders
tend to be less critical than newer (glassfibre) ones.

- Check you manufacturer's recommendations. They usually know what they
are doing, and some manuals are very thorough.
- Check your gap seals' condition regularly.

At 13:52 24 May 2013, wrote:
On Wednesday, May 22, 2013 12:20:54 PM UTC-5, soartech wrote:
What is lost without them? One point of glide? What about sink rate?
=20
Is this just for racers? My glider does not have them.
=20
Does anyone have any facts on this?
=20
Thanks.

When I got my LS8-18 off the boat in 2001 it did not have any mylar
externa=
l seals on the top or bottom of the ailerons. It did come with two
interna=
l roll-seals on each side that seem to work very well. I'm still flying
th=
at way and have no indications that my glider's performance is lacking -
qu=
ite the opposite. Aileron forces are delightfully low, no friction, no
bre=
ak-out forces. The gap itself is in the turbulent part of the wing and
add=
itional sealing would hardly make a difference. This would be different
on=
a -27 or -29 where the bottom flow is laminar into the aileron/flap area
a=
nd Schleicher is using seals consequently.
I like the simplicity of my set-up.
Herb